1. Field of the Invention
The present invention relates to a closure operating device and, more particularly, to a casing structure for such a closure operating device.
2. Description of the Prior Art
It is well known to provide a closure operating device, mounted on a wall, to mechanically displace an overhead door between open and closed positions thereof. Such closure operating devices typically include a control unit for controlling the operation of a power actuator operatively connected to an overhead door. The power actuator is mounted to a casing which defines a compartment for receiving electric and electronic components forming part of the control system. The power actuator typically includes an electric motor having an output shaft which is connected to one or more shafts journaled to the casing. The shafts are typically connected to each other via a series of endless chains extending over sprocket wheels keyed onto the shafts.
Access to the sprocket wheels is normally prevented by the casing. When it is desired to have access to the sprocket wheels, the operator has to remove the casing from the wall on which it is mounted so as to expose a rear open side thereof.
It has been found that there is a need for a new casing which could selectively allow and prevent access to parts housed therein while remaining mounted on a mounting surface, such as a wall.
The control unit of closure operating devices of the type described hereinbefore generally includes a limit switch mechanism for automatically interrupting power transmission to the power actuator when the closure has been displaced to its fully open and closed positions. Such a limit switch mechanism generally comprises a pair of switch actuators threadably engaged on a threaded shaft coupled to the output shaft of the device. These switch actuators are normally engaged by an anti-rotation member to cause axial displacement of the switch actuators along the threaded shaft when the latter is rotated. Adjustment of the switch actuators is effected by first simultaneously disengaging the anti-rotation member from the switch actuators and then independently rotating the actuators to cause axial movement thereof on the threaded shaft. By simultaneously unlocking the switch actuators, there is a risk that one of the switch actuators is accidentally displaced out of its functional position while the other one is being adjusted.
It is therefore an aim of the present invention to provide a closure operating device having a new casing which is adapted to provide access to parts housed therein while the casing is mounted to a mounting surface.
It is also an aim of the present invention to provide a new limit switch mechanism adapted to reduce the risk of altering the adjustment of a part thereof while adjusting the position of another part thereof.
Therefore, in accordance with the present invention, there is provided a closure operating device comprising a casing adapted to be mounted to a mounting surface and defining an interior space accessible through an access opening, a lid mounted to said casing for pivotal movement between an open position thereof to provide access to said interior space through said access opening and a closed position thereof to prevent access to said interior space, said lid defining a compartment, an output shaft journaled to said casing and extending through said interior space, a power actuator operatively connected to said output shaft for opening and closing a closure, and a control system for controlling operation of said power actuator, said control system being at least partly housed within said compartment of said lid.
In accordance with a further general aspect of the present invention, there is provided a limit switch mechanism for controlling the operation of a motor over a selected range of movement, comprising a casing, a motor-driven threaded shaft journaled to said casing, first and second switch actuators threadably engaged on said threaded shaft and adjustably positionable thereon, first and second limit switches mounted at spaced-apart locations on said casing adjacent to said threaded shaft so as to be respectively actuated by said first and second switch actuators upon reaching respective predetermined positions on said threaded shaft, at least one anti-rotation member connected to said casing for movement between a first position for engaging said first and second switch actuators to prevent rotation of said first and second switch actuators on said threaded shaft and cause simultaneous axial displacement of said first and second switch actuators along said threaded shaft in response of a rotational movement thereof, and a selected one of a second position and a third position for allowing a respective one of said first and second switch actuators to be disengaged from said anti-rotation member while the other one of said first and second switch actuators remains locked against rotation by said anti-rotation member such that a position of said selected one of said first and second switch actuators may be adjusted.